<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>学习标题</title>
</head>
<body>

<h1>这是标题</h1>
<h2>这是标题</h2>
<h3>这是标题</h3>
<h4>这是标题</h4>
<h5>这是标题</h5>
<h6>这是标题</h6>

</body>
</html>